Add in ShopHandler interface

src/main/java/com/alttd/playershops/api/ShopHandler.java

@@ -0,0 +1,72 @@
+package com.alttd.playershops.api;
+
+import com.alttd.playershops.shop.AbstractShop;
+import org.bukkit.Location;
+import org.bukkit.Material;
+import org.bukkit.block.Block;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+import java.util.UUID;
+
+public interface ShopHandler { // TODO finish docs
+
+    /**
+     * Get the shop at a given location
+     *
+     * @param location Location of the shop
+     * @return Shop at the given location or <b>null</b> if no shop is found there
+     */
+    AbstractShop getShop(Location location);
+
+    /**
+     * Checks whether there is a shop at a given location
+     * @param location Location to check
+     * @return Whether there is a shop at the given location
+     */
+    boolean isShop(Location location);
+
+    /**
+     * Get a collection of all loaded shops
+     *
+     * This collection is safe to use for looping over and removing shops.
+     *
+     * @return Read-only collection of all shops
+     */
+    Collection<AbstractShop> getShops();
+
+    /**
+     * Add a player's custom shop limit
+     *
+     * @param uuid The uuid linked to this player
+     * @param limit The new maximum amount of shops this player can have
+     */
+    void addPlayerLimit(UUID uuid, int limit);
+
+    /**
+     * Get the maximum amount of shops this player is allowed to have
+     *
+     * @param uuid The uuid linked to this player
+     * @return The limit of shops for this player
+     */
+     int getShopLimit(UUID uuid);
+
+    /**
+     * Checks wether this block is valid to be used as a shop
+     *
+     * @param block the block to check
+     * @return true if this block can be a shop
+     */
+     boolean isShopMaterial(Block block);
+
+    /**
+     * Get all the shops owned by a player
+     *
+     * @param uuid The uuid linked to this player
+     * @return List of shops this player owns
+     */
+    List<AbstractShop> getShops(UUID uuid);
+
+    ArrayList<Material> getShopMaterials();
+}